CARBON is the new Vietnam: American students want out. Or rather, they want their universities to stop investing in firms that profit from climate-changing carbon. Last month Stanford said it would no longer invest any of its $19 billion endowment in coal firms.

Was this a brilliant piece of market timing, given Mr Obama’s announcement on June 2nd of tough new carbon regulations? Not really: coal shares were already down in anticipation of the new rules, and barely moved when the news broke. Shares in Peabody Energy, America’s largest coal firm, are down four-fifths from their high in June 2008. Perhaps the trustees of Stanford’s endowment (including Tom Steyer, a rich environmentalist) concluded that ditching coal is now an affordable public-relations strategy.